Field of the Disclosure
The present disclosure relates to dynamic broadcast. In particular, the present disclosure relates to a terminal and a corresponding receiving method, a dynamic broadcast system and method, a controller device, a control method and a computer readable non-transitory medium.
Description of Related Art
The scarce terrestrial frequency spectrum is an important factor for the development of wireless communication. Nowadays broadcast services take up a significant part of the frequencies in the (e.g. UHF or VHF) broadcast bands, which are ideal for in-house reception. Thanks to digitization, the spectrum usage efficiency of broadcast services has been increased largely compared to the times of analog. However, the network operation remains still static, i.e. the transmission parameters are fixed and invariable, transmitter power is constant, and services are delivered in pre-determined channels. Such traditional broadcast network has very low requirements on the receivers. Neither a feedback channel nor a content storage device is necessitated, and a channel scan process is usually only needed when the terminal device is powered on for the first time, since the transmission parameters for each TV channel will be stored for later tune-in.
Consumer electronics industry develops rapidly, and user terminals are becoming more and more powerful. Recently, a trend in the field of consumer TV is the development of “hybrid user terminals”” which can acquire media content via broadband networks, such as xDSL, DOCSIS or satellite communication links and, eventually, even via wireless Internet networks (e.g. via a Long Term Evolution (LTE) network) or other wireless data networks in addition to traditional broadcast networks. Although such receivers allow the seamless access to both Internet and broadcast content, there are almost no inter-working features between the two delivery means. Another notable point is that more and more TVs and Set-top-boxes (STB) are equipped with huge storage devices and this is essential for the time-shifted consumption of media content. The content storage can be controlled normally by the user or a scheduler to build personal television channels, but still is neither controlled by either network nor influences what happens in the network. In certain cases, providers of Pay-TV-services have started to pre-download content onto the storage devices in order to provide viewers with more choice of programs.
These new capabilities of user terminals, namely the available broadband network access and a storage device with reasonable capacity, may not only be utilized to enhance the user experience, but also to reduce the TV programs delivery cost and to increase both the efficiency of spectrum usage and the energy efficiency of the whole system.
Firstly, taking advantage of the presence of the second delivery means (the broadband network), the ingrained TV viewing habits can be exploited to optimize the TV content distribution. Broadcast is optimal for a massive audience, since the network operation cost is almost independent of the size of its audience for a given coverage area, which indicates that the more users it serves, the lower the cost for the individual user remains. In contrast, the cost of broadband delivery increases generally as the viewer number gets larger and in case of unicast the relation is nearly linear. This implies that for those events which have a small audience, delivery via a broadband network may be more cost-efficient.
Moreover, managed by the user terminal, the storage device is able to store the contents which are planned to be repeated by the broadcaster in the following 14 days or so and which the user is predicted to have strong interest to watch. In this way the on-air viewer numbers of repeated TV content can be reduced significantly and the skewness of the channel popularity distribution is considerably reinforced. Suppose that the remaining number of on-air viewers falls below a pre-defined threshold, the content then should be reallocated to the broadband channel, thereby freeing capacity in the broadcast channels or even the spectrum.
Further, due to the fact that TV viewer numbers vary significantly during a day, the freed capacity has also a strong time-dependency. In the prime-time hours freed data rates will be much less than e.g. over night. To make a better use of the spectrum a new delivery strategy is defined, which uses the broadcast capacity over night to pre-transmit some of the TV content to user terminals. At a pre-signaled broadcast time these terminals can then play back the content from their storage device directly. As a result, the number of terminals which have to receive the live broadcast will be lowered and eventually this live content may also be moved to a broadband channel. Similarly, the pre-transmission can also be placed in the broadband channel during low-traffic hours, so the load of the broadband network during day-time can be reduced.
The freed capacity is extremely valuable for both broadcasters and other wireless communication network operators. The following possible usages can be considered for instance: Deliver more broadcast services; adjust the transmission parameters to a more robust mode, with the purpose that the power consumption of the transmitter can be reduced; and shut down certain broadcast channels temporally and make the frequencies available to secondary wireless service providers for a certain time period.
The development of new wireless communication systems is often restricted by a lack of available frequency spectrum. On the other hand, many frequency bands allocated to specific technologies are often underutilized. TV White Spaces (TVWS) are frequency bands which are allocated to terrestrial broadcasting systems, but are locally not usable by broadcast network operators due to interference planning or missing broadcasting infrastructure. Regulation authorities, standardization bodies and research institutes as well as industry are seeking ways to make use of these valuable frequency resources for secondary wireless communication (secondary users, generally called white space devices WSDs).
There are some restrictions on the efficient use of TVWS spectrum. On the one hand, primary spectrum users (primary users, predominantly terrestrial broadcast networks), have to be protected against harmful interference from secondary users operating in the same frequency bands. On the other hand, overly stringent (conservative) TVWS usage permissions can significantly reduce TVWS availability. Furthermore, TVWS availability may vary from location to location, typically offering less capacity for high population density areas.
A known technology for managing TVWS spectrum access, as for instance stated in the ECC report 159, is the use of geolocation databases (or white space databases). All relevant spectrum usage information including primary transmitter locations, terrain and propagation characteristics and transmission powers have to be stored in these databases. WSDs must know their position and must consult the white space database before they are put into operation. By this query, a WSD can find out usable frequency bands and maximum permitted transmit powers at its location. However, white space databases cannot overcome the issue of TVWS spectrum not being available in a certain location, nor can they handle the potential interference to broadcast receivers.
The “background” description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventor(s), to the extent it is described in this background section, as well as aspects of the description which may not otherwise qualify as prior art at the time of filing, are neither expressly or impliedly admitted as prior art against the present disclosure.